Make user mentions case-insensitive

changelogs/unreleased/make_user_mentions_case_insensitive.yml

+---
+title: Make user mentions case-insensitive
+merge_request: 10285
+author: blackst0ne

lib/banzai/filter/user_reference_filter.rb

@@ -60,7 +60,7 @@ module Banzai
         self.class.references_in(text) do |match, username|
           if username == 'all' && !skip_project_check?
             link_to_all(link_content: link_content)
-          elsif namespace = namespaces[username]
+          elsif namespace = namespaces[username.downcase]
             link_to_namespace(namespace, link_content: link_content) || match
           else
             match
@@ -74,7 +74,7 @@ module Banzai
       # The keys of this Hash are the namespace paths, the values the
       # corresponding Namespace objects.
       def namespaces
-        @namespaces ||= Namespace.where_full_path_in(usernames).index_by(&:full_path)
+        @namespaces ||= Namespace.where_full_path_in(usernames).index_by(&:full_path).transform_keys(&:downcase)
       end
 
       # Returns all usernames referenced in the current document.

spec/lib/banzai/filter/user_reference_filter_spec.rb

@@ -83,6 +83,14 @@ describe Banzai::Filter::UserReferenceFilter, lib: true do
       expect(doc.css('a').length).to eq 1
     end
 
+    it 'links to a User with different case-sensitivity' do
+      user = create(:user, username: 'RescueRanger')
+
+      doc = reference_filter("Hey #{user.to_reference.upcase}")
+      expect(doc.css('a').length).to eq 1
+      expect(doc.css('a').text).to eq(user.to_reference)
+    end
+
     it 'includes a data-user attribute' do
       doc = reference_filter("Hey #{reference}")
       link = doc.css('a').first